57 lines
1.7 KiB
Go
57 lines
1.7 KiB
Go
//
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// Copyright 2021 The Sigstore Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sshsig
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import (
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"io"
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"golang.org/x/crypto/ssh"
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)
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// Verify verifies the signature of the given data and the armored signature using the given public key and the namespace.
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// If the namespace is empty, the default namespace (file) is used.
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func Verify(message io.Reader, armoredSignature []byte, publicKey []byte, namespace string) error {
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if namespace == "" {
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namespace = defaultNamespace
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}
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decodedSignature, err := Decode(armoredSignature)
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if err != nil {
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return err
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}
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desiredPk, _, _, _, err := ssh.ParseAuthorizedKey(publicKey)
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if err != nil {
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return err
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}
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// Hash the message so we can verify it against the signature.
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h := supportedHashAlgorithms[decodedSignature.hashAlg]()
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if _, err := io.Copy(h, message); err != nil {
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return err
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}
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hm := h.Sum(nil)
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toVerify := MessageWrapper{
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Namespace: namespace,
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HashAlgorithm: decodedSignature.hashAlg,
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Hash: string(hm),
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}
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signedMessage := ssh.Marshal(toVerify)
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signedMessage = append([]byte(magicHeader), signedMessage...)
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return desiredPk.Verify(signedMessage, decodedSignature.signature)
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}
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